Normally liquids are clarified by a combination of flocculation and decantation at atmospheric pressure. Solid/liquid mixtures are introduced to containers or tanks of sufficient size and depth to allow the solids to sink by gravity below a clear liquid level, and the liquid is then removed by overflowing the container. Often, the thickened slurries are removed from the bottoms of the clarifiers by mechanical methods such as rakes, screws, buckets, shovels, etc. The solid/liquid mixtures normally treated are metal, mineral, industrial, sewage or other materials that have been prepared for separation by processes such as screening, grinding or classifying by screw, rake or other preparatory processes.
Apart from separating liquids from solids, it is frequently required to separate the solid classes in a mixture from each other; i.e. the separation of metals from sand, marketable minerals from gangue material or coarse particles from fine ones.
Three general methods are commonly in use to separate solids from solids in a liquid medium: gravity methods, froth flotation and heavy media sink/float separation.
Gravity separation of metals and minerals is normally carried on by the use of mineral jigs, shaker tables, sluice boxes, belts and pulleys, cones, cyclones, rakes, screws, etc. Many gravity separators have relatively low throughput capacities and require high ratios of water to solids, in the range of 5:1 to 10:1 by weight. Minerals of different specific gravities are separated as they are washed across the surfaces of various devices.
Froth flotation of mineral concentrates is normally carried on in tanks or cells fitted with agitators and aerators. The liquid is treated with chemical additives to cause one mineral to sink while another floats to the surface in a froth which affects the separation of the minerals of opposite surface tension characteristics.
Heavy media sink/float separators utilize a heavy media or thickened liquid to effect a gravity separation by floating the light particles and sinking the heavy ones.
It is an object of the instant invention to remove some of the deficiencies of the above prior art by providing a device which may be produced and operated more inexpensively and which is less complex to build and operate than those of the prior art. In principal, the instant invention uses the basic technique of a siphon to pull a liquid containing solid particles vertically upward through a tall column and hence a classic siphon must be considered prior art.
To date, we have found no evidence in practice, in literature or in patents to support the fact that devices utilizing the siphon height of a liquid are in use to clarify liquids, classify solids, to comminute solids or to destroy water borne living organisms. The siphon height of a liquid is the height to which a liquid will rise under vacuum at a given barometric pressure and is approximately 34 feet (10.363 m) for water and 29.92 inches (0.760 m) for mercury at sea level.